This invention relates to disc type brakes and particularly to fail-safe disc brakes in which mechanical actuation of the brake friction elements is provided by a spring or other mechanical energy storing apparatus. Release of the brake is provided by hydraulic or air pressure for moving the brake friction elements out of braking engagement and holding them in the released or off position. In the event of air of hydraulic pressure failure, mechanical actuation of the brake will take place automatically.
Brakes of this type have utilized relatively long compression springs with relatively large diameters to produce the necessary braking forces. This has resulted in a brake requiring greater space than is desirable for brake installations.
The space required is substantially greater for brakes where high braking forces or high torque are desired because they require either an increased number of springs, a series of stacked rotor and stator elements or a large friction radius or brake diameter. This increased need for space has also increased the cost of the brake.
The high force compression springs used with these brakes have high spring rates and require frequent adjustments with small amounts of lining wear because of the limited travel of the springs. This limitation and the others set forth above have restricted the torque forces which can be economically handled by fail-safe disc brakes.